If a2 + 1 = a,  then the value of a12 + a6 + 1 is from Quan

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 Multiple Choice QuestionsMultiple Choice Questions

221.

If fraction numerator 4 straight x minus 3 over denominator straight y end fraction space plus space fraction numerator 4 straight y minus 3 over denominator straight y end fraction space plus space fraction numerator 4 straight z minus 3 over denominator straight z end fraction space equals space 0 comma then the value of 1 over straight x space plus space 1 over straight y space plus space 1 over straight z is

  • 3

  • 4

  • 6

  • 9

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222.

If x2 = y + z,  y2 = z + x  and z2 = x + y, then the value of 
   fraction numerator 1 over denominator 1 plus straight x end fraction space plus space fraction numerator 1 over denominator 1 plus straight y end fraction space plus space fraction numerator 1 over denominator 1 plus straight z end fraction is

  • 1

  • 2

  • 0

  • -1

30 Views

223.

If x2 - 3x + 1 = 0,  then the value of straight x squared space plus space straight x space plus space 1 over straight x space plus space 1 over straight x squared is

  • 2

  • 6

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  • 10

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224.

If a2 + b2 + 4c2 = 2(a + b - 2c) - 3 and a, b, c are real, then the value of (a2 + b2 + c2) is

  • 3 1 fourth

  • 2

  • 2 1 fourth

  • 3

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225.

If a + b + c = 0, then the value of
open parentheses fraction numerator straight a space plus space straight b over denominator straight c end fraction space plus space fraction numerator straight b space plus space straight c over denominator straight a end fraction space plus space fraction numerator straight c space plus space straight a over denominator straight b end fraction close parentheses space open parentheses fraction numerator straight a space over denominator straight b space plus space straight c end fraction space plus space fraction numerator straight b space over denominator straight c space plus space straight a end fraction space plus space fraction numerator straight c space over denominator straight a space plus space straight b end fraction close parentheses is

  • 9

  • 0

  • 8

  • -3

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226.

If straight a space asterisk times space straight b space equals space straight a space plus space straight b space plus space straight a over straight b comma then the value of 12 * 4 is

  • 48

  • 19

  • 20

  • 21

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227.

If a, b and c are non-zero, straight a space plus space 1 over straight b space equals space 1 space space space and space straight b space plus space 1 over straight c space equals space 1 then the value of abc is

  • -3

  • 1

  • -1

  • 3

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228.

If x ≠ 0,  y ≠ 0  and z ≠ 0 and 
1 over straight x squared space plus fraction numerator begin display style 1 end style over denominator begin display style straight y squared end style end fraction space plus space fraction numerator begin display style 1 end style over denominator begin display style straight z squared end style end fraction space equals space 1 over xy space plus space 1 over yz space plus space 1 over zx,  then the relation among x, y and z is

  • 1 over straight x space plus space 1 over straight y space plus space 1 over straight z space equals space 0

  • x = y = z

  • x + y + z = 0

  • x + y = z

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229.

If x2 + y2 + z2 = 2(x - y - z) - 3, then the value of 2x - 3y + 4z is (assume that x, y and z) are all real numbers).

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  • 9

  • 1

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230.

If a2 + 1 = a,  then the value of a12 + a6 + 1 is

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  • -3

  • 1


B.

3

a2 + 1 = a
  rightwards double arrow space space space space straight a space plus space 1 over straight a space equals space 1
On Squaring both sides, we get,
           straight a squared space plus space 1 over straight a squared space plus space 2 space equals space 1
rightwards double arrow space space space straight a squared space plus space 1 over straight a squared space equals space minus 1
On Cubing both sides, we get,
        space space space open parentheses straight a squared space plus space 1 over straight a squared close parentheses cubed space equals space left parenthesis negative 1 right parenthesis cubed
rightwards double arrow space space straight a to the power of 6 space plus space 1 over straight a to the power of 6 space plus space 3 straight a squared space cross times space 1 over straight a squared open parentheses straight a squared space plus space 1 over straight a squared close parentheses space equals space minus 1 space space rightwards double arrow space space straight a to the power of 6 space plus space 1 over straight a to the power of 6 space plus space 3 space cross times space minus 1 space equals space minus 1
rightwards double arrow space space space space straight a to the power of 6 space plus space 1 over straight a to the power of 6 space plus space 1 space equals space 3 space space space space space space space space space space space space space... left parenthesis straight i right parenthesis
If we put a = 1  in equation (i), it satisfies the equation. i.e. a = 1.
Now,  put a = 1. in  a12 + a6 + 1 i.e (1)12 + (1)6 + 1 = 3

             

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